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Article
Publication date: 8 December 2010

Subhash Yaragal, K S Babu Narayan, Katta Venkataramana, Kishor Kulkarni, H C Chinnagiri Gowda, G R Reddy and Akanshu Sharma

Concrete in structures is likely to be exposed to high temperatures during fire. The probability of its exposure to elevated temperatures is high due to natural hazards, accidents…

160

Abstract

Concrete in structures is likely to be exposed to high temperatures during fire. The probability of its exposure to elevated temperatures is high due to natural hazards, accidents and sabotages. Therefore, the performance of concrete during and after exposure to elevated temperature is a subject of great importance and interest to the designer. Popular normal strength grades of concrete produced by Ready Mix Concrete (RMC) India, Mangalore have been used in production of test specimens (150 mm cubes), cured and tested by destructive method for gathering data on strength characteristics. Later, these test samples were subjected to elevated temperatures ranging from 100°C to 800°C, in steps of 100°C with a retention period of 2 hours. After exposure, weight losses and the residual compressive strength retention characteristics are studied. Test results indicated that weight and strength significantly reduces with an increase in temperature. Residual compressive strength prediction equations are proposed for normal strength concretes subjected to elevated temperatures.

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Journal of Structural Fire Engineering, vol. 1 no. 4
Type: Research Article
ISSN: 2040-2317

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Article
Publication date: 13 March 2017

Swapnil K. Shirsath and Subhash C. Yaragal

This study reports the performance of thermally deteriorated concrete with and without fibres. Attempts have been made to find the suitable performance of steel polypropylene (PP…

181

Abstract

Purpose

This study reports the performance of thermally deteriorated concrete with and without fibres. Attempts have been made to find the suitable performance of steel polypropylene (PP) hybrid fibre combination that could significantly enhance the performance of mechanical properties at elevated temperatures.

Design/methodology/approach

In this experimental investigation, concrete cubes of 100 mm in size of various compositions were cast and water-cured for 28 days, and later exposed to elevated temperatures of either 200 or 400°C or 600 and or 800°C with a retention period of 2 h. The properties like change in colour and percentage weight loss were evaluated. Ultrasonic Pulse Velocity test was used to obtain qualitative information of strength variation. Residual strength of thermally deteriorated concrete specimen was measured by destructive testing.

Findings

Steel fibre volume fraction of 1 per cent improves the compressive strength of concrete in the temperature range of 400 to 800°C. The addition of steel fibre and PP fibre (Mix 3) improves the splitting strength of the concrete at elevated temperature range of 400 to 600°C.

Originality/value

Performance enhancement is observed with hybrid fibres for temperature endurance of concrete.

Details

Journal of Structural Fire Engineering, vol. 8 no. 1
Type: Research Article
ISSN: 2040-2317

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Article
Publication date: 17 February 2015

Subhash Yaragal, Murugesh Kittur and K. Narayan

Concrete is found to undergo degradation when subjected to elevated temperatures during an accidental event, such as fire and lose substantial amount of its original strength. The…

96

Abstract

Concrete is found to undergo degradation when subjected to elevated temperatures during an accidental event, such as fire and lose substantial amount of its original strength. The loss of strength in concrete is mainly attributed to the decomposition of Calcium Silicate Hydrate (C-S-H) and release of chemically bound water, which begins when the exposure temperature exceeds 500°C. When such a concrete is supplied with water and allowed to recure, it is found to recover substantial amount of its lost strength. This work is carried out to investigate the effect of recuring on strength recovery of un-blended and blended concrete specimen (100 mm cubes) subjected to elevated temperatures from 400°C to 700°C, in steps of 100°C, for a retention period of two hours at the designated temperatures. The concrete cubes immediately after exposure were subjected to thermal shock by quenching them in water, and then temperature of thermally shocked concrete is allowed to cool to room temperature. The cooled specimen were then recured in water for 1, 3, 7, 14, 21, 28, 56 days and tested for compressive strength recovery. These studies were carried out for Portland Cement (PC) based concrete and Portland & Granulated Blast Furnace Slag (70% PC + 30% GGBS) based concrete (blended concrete), and some interesting results are presented and discussed in this paper.

Details

Journal of Structural Fire Engineering, vol. 6 no. 1
Type: Research Article
ISSN: 2040-2317

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